The invention relates to a superheated steam generator comprising a bank of U-tubes.
Steam generators of this kind are for example used in the case of pressurized-water nuclear reactors and serve to produce steam by using the pressurized water of the reactor as primary fluid for heating and vaporizing the feed water.
These steam generators comprise a water drum, consisting of two portions separated by a partition, for supplying the tubes of the bank with hot primary fluid and for discharging the cooled primary fluid after it has passed through the tube bank and has come into thermal contact with the feed water which is to be vaporized. The U-tubes of the bank are fixed on a tube plate, of which one face, the inlet face, is situated on the water drum side. The ends of the tubes are flush with this inlet face, and each of the tubes is thus in communication with both the feed portion and the evacuation portion of the water drum.
The bank of tubes disposed vertically inside the upper part of the steam generator, the outer casing of which is known as the "secondary casing", passes through the other face of the tube plate, i.e., its outlet face.
The water drum and the secondary casing are welded on the tube plate, one on each side of the latter, i.e., at its inlet and outlet faces respectively.
The bank of U-tubes is itself disposed inside a casing coaxial to the secondary casing and located inside the latter, in such a manner that an annular space is left between the outer wall of the tube bank casing and the inner wall of the secondary casing.